Known monocoques made of a composite material, in particular carbon fiber, are generally manufactured by fixing to each other by means of adhesives and/or mechanical members, for example bolts, composite material components which are moulded separately. Such known monocoques are characterized both by a high cost, since the whole structure is not intended for the exploitation of the potentialities of the composite material, and by a medium level of repeatability, substantially due to the high use of manual operations within the manufacturing process. As a matter of fact, the monocoques are made of numerous components, all moulded separately by means of a manual stratification, which are then assembled manually or by means of gluing templates. The components are therefore first produced and subsequently assembled, by following the classic production and assembly process typical of the motor vehicle industry. The components are generally obtained by means of moulding processes with fiber carbon substrates pre-impregnated with resin, known as pre-preg, which are layered manually and cured in an autoclave. This process requires long manual workings and expensive materials, furthermore it does not ensure as repeatability comparable with all the other parts of the vehicle. The monocoques produced until now are therefore also not much suitable for the mass production. The manufacturing processes further require very articulated systems which lead, in most cases, to have tens of moulds reserved for producing a single component. Moreover, the products must be disadvantageously worked within few days since the material highly degrades if left at room temperature before the cure cycle, so that such known process can hardly thee sudden production stops and involves a high risk of producing rejects.
The known monocoques are therefore very expensive and difficult to produce in a high mass due to the high number of few repeatable components. The parts are mainly made up of pre-impregnated fibers, which are expensive and require a high deftness. Their manufacturing process is further characterized by a clear separation between production and assembly, the used moulds have a limited life and the production cycle in which they are used provides for the use of a lot of moulds in view of a single manufactured piece.
U.S. Pat. No. 5,079,055 discloses a reinforcement member for composite material products, which member is provided with an insert with a threaded hole. However, during the moulding of the composite material with the reinforcement member, such threaded hole may be disadvantageously filled with resin, since it is open to the outside.
In order to solve this disadvantage, FR 2783196 discloses a spacer provided with an insert with a threaded hole which is closed by one or more plugs. A plug is removed with a mechanical working after the moulding of the composite material. However, this known process is more expensive, since it requires the application and the removal of the plugs from the threaded hole, and further it does not allow a precise arrangement of the threaded hole with respect to the moulded product if the relative position of the inserts with respect to the product is not perfect.